Disc cartridge

ABSTRACT

A disc cartridge housing a driving rotating unit and adapted to be loaded along with the driving rotating unit on a recording and/or reproducing apparatus. A shutter mechanism for opening/closing an opening provided in a main cartridge body portion includes two shutter members movable along the major surface of the main cartridge body portion. An area in which the first shutter member and the second shutter member are moved is delimited by first and second wall sections arranged facing each other. The first and second shutter members are intruded into a spacing defined between the first and second wall sections. The first and second wall sections are arranged in the portions of the main cartridge body portion facing the major surface of the disc-shaped recording medium so that the wall sections face each other with a pre-set separation in-between. The main cartridge body portion is formed with first and second openings facing the first and second wall sections. These first and second openings are adapted for exposing a portion of the signal recording region of the disc-shaped recording medium to outside across the inner and outer rims of the disc-shaped recording medium and for allowing the center of the disc-shaped recording medium to face outwards. The first and second shutter members are arranged for movement between the first and second wall sections. The second shutter member is rotated in association with the first shutter member by having its portion engaged and held by an engagement holding portion provided on said first shutter member.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a disc cartridge for housing adisc-shaped recording medium, such as an optical disc or amagneto-optical disc, loaded on a recording and/or reproducingapparatus. More particularly, it relates to a disc cartridge in which ashutter mechanism adapted for opening or closing an aperture formed in amain cartridge body unit is made up of two shutter members adapted forbeing moved along the major surface of the main cartridge body unit.

[0003] 2. Description of the Related Art

[0004] There has hitherto been used a disc cartridge housing an opticaldisc, a magneto-optical disc or a magnetic disc and which is loadedtherewith on a recording and/or reproducing apparatus.

[0005] As this type of the disc cartridge, there is known such a devicedescribed in the U.S. Pat. Nos. 4,510,546 and 4,876,619.

[0006] With the disc cartridge described in these publications, a discas a recording medium is rotationally housed within a main cartridgebody unit which is rectangular in shape. The main cartridge body unithas a recording and/or reproducing opening for allowing a portion of thehoused magnetic disc to be exposed to outside across the inner and outerrims of the disc. This main cartridge body unit carries a shuttermember, rectangular in cross-section, adapted to be moved along thefront side of the main cartridge body unit for opening/closing therecording and/or reproducing opening.

[0007] With the disc cartridge, carrying the shutter member foropening/closing the opening formed in the main cartridge body unit, theopening is perpetually kept closed by the shutter member to preventaffixture of a fingerprint of a user inadvertently touching therecording surface of the disc or to prevent intrusion of dust and dirtvia the opening to assure reliable disc protection.

[0008] As a disc cartridge housing a disc as an information recordingmedium, there is known such a one as described in the U.S. Pat. No.4,614,990.

[0009] In the disc cartridge described in this Publication, a shuttermember is provided in parallel with the inserting direction of the disccartridge into the recording and/or reproducing apparatus, so that, oninsertion of the disc cartridge into the recording and/or reproducingapparatus, the shutter member is locked or unlocked by an unlockmechanism provided on the recording and/or reproducing apparatus, at thesame time as the shutter member is moved in a direction of opening theopening, with the result that the shutter member can be opened or closedby a simplified mechanism.

[0010] As a disc cartridge housing a disc as an information recordingmedium, there is known such one as disclosed in the U.S. Pat. No.5,570,252. The disc cartridge disclosed in this Publication has anopening in a lateral surface of the main cartridge body unit. Themagnetic head is introduced via this opening into the inside of the disccartridge into sliding contact with the signal recording region of themagnetic disc. In this disc cartridge, the shutter member adapted foropening/closing the opening is mounted for performing movement along alateral side of the main cartridge body unit.

[0011] Meanwhile, with the disc cartridge disclosed in the U.S. Pat.Nos. 4,510,546 and 4,876,619, in which the shutter member is moved alongthe outer surface of the main cartridge body unit, dust and dirt tend tobecome affixed to the surface of main cartridge body unit along whichslides the shutter member. The dust and dirt, thus deposited, tend todrop into the inside of the main cartridge body unit with movement ofthe shutter member, thus contaminating the disc housed in the maincartridge body unit.

[0012] Also, since the shutter member is moved in a directionperpendicular to the inserting direction of the disc cartridge into therecording and/or reproducing apparatus, it is necessary to provide acomplex opening/closing mechanism, such as a rotary arm, thuscomplicating the mechanism of the recording and/or reproducingapparatus.

[0013] Similarly, with the disc cartridge disclosed in the U.S. Pat. No.4,614,990, in which the shutter member is moved along the outer side ofthe main cartridge body unit, dust and dirt tend to become affixed tothe surface of the main cartridge body unit along which the shuttermember is moved, so that the dust and dirt tend to drop into the insideof the main cartridge body unit to contaminate the disc housed in themain cartridge body unit.

[0014] In the disc cartridge disclosed in the U.S. Pat. No. 5,570,252,in which the magnetic bead is inserted into the inside of the maincartridge body unit via the narrow opening provided in the lateral sideof the main cartridge body unit, there are imposed limitations on therecording and/or reproducing mechanism used. Such disc cartridge isextremely difficult to apply to an optical disc used in an opticalpickup device. Moreover, the shutter member is configured foropening/closing the opening which is narrow in width and longer inlength than in width, the shutter member is also narrow in width andlonger in length to render it difficult to realize stable movement ofthe shutter member.

SUMMARY OF THE INVENTION

[0015] It is therefore an object of the present invention to provide adisc cartridge in which it is possible to prevent dust and dirtdeposited on the outer surface of the main cartridge body unit inassociation with movement of the shutter member from being intruded intothe inside of the main cartridge body unit to assure reliable protectionof the disc-shaped recording medium housed in the main cartridge bodyunit.

[0016] It is another object of the present invention to provide a disccartridge having a shutter mechanism including a recording and/orreproducing opening larger in size than the main cartridge body unithousing the disc-shaped recording medium to enable use of thelarge-sized recording and/or reproducing mechanism to permit thelarge-sized opening to be opened or closed reliably.

[0017] It is still another object of the present invention to provide adisc cartridge that is able to close the opening in the main cartridgebody unit reliably to protect the disc-shaped recording medium housed inthe main cartridge body unit reliably.

[0018] It is yet another object of the present invention to provide adisc cartridge reduced in thickness and a recording and/or reproducingapparatus employing the disc cartridge and which is also reduced inthickness.

[0019] A disc cartridge according to the present invention is such adisc cartridge housing a disc-shaped recording medium such as an opticaldisc or a magneto-optical disc and which is loaded along with thedisc-shaped recording medium on the recording and/or reproducingapparatus. A shutter mechanism for opening/closing an opening providedin the main cartridge body unit includes two shutter members movablealong the major surface of the main cartridge body unit. An area inwhich are moved the first shutter member and the second shutter memberof the main cartridge body unit is constituted by first and two wallsections arranged facing each other. The first and second shuttermembers are intruded into a spacing defined between the first and twowall sections.

[0020] The disc cartridge includes a main cartridge body unit and firstand second shutter members. The main cartridge body unit rotatablyhouses the disc-shaped recording medium, and includes first and secondwall sections facing the portion of the disc cartridge in turn facingthe major surface of the disc-shaped recording medium at a pre-setseparation from each other. The main cartridge body unit also includes arecording and/or reproducing opening facing the first and second wallsection for exposing a portion of the signal recording region of thedisc-shaped recording medium to outside and a driving opening adapted toallow the center of the disc-shaped recording medium to be exposed tooutside. The first and second shutter members include first and secondshutter members adapted for opening/closing the recording and/orreproducing opening and the driving opening. The first and secondshutter members are adapted to be moved between the first and secondwall sections.

[0021] The first shutter member is supported so that its one end will bemoved along the position proximate to the outer rim of the circularmedium housing section formed on the main cartridge body unit forrotationally housing the disc-shaped recording medium. The secondshutter member is supported by the main cartridge body unit inassociation with the rotation of the first shutter member by having itsportion engaged and held by the engagement holding portion provided onthe first shutter member.

[0022] Another disc cartridge according to the present invention is sucha disc cartridge rotationally housing a disc-shaped recording medium ina main cartridge body unit made up of an upper half cartridge and alower half cartridge abutted and connected to each other. The disccartridge includes a recording and/or reproducing opening provided inthe main cartridge body unit for exposing a signal recording region ofthe disc-shaped recording medium at least across the inner and outerrims of the disc-shaped recording medium, a driving opening for entranceof the rotating driving means for the disc-shaped recording medium and ashutter mechanism for opening/closing the driving opening. The shuttermechanism provided on the disc cartridge includes a first shutter memberfor opening/closing mainly the recording and/or reproducing opening anda second shutter member for opening/closing mainly the driving opening.The first shutter member includes a shutter portion for opening/closingthe recording and/or reproducing opening and the driving opening, amovement causing portion for causing movement of the shutter portion anda connecting portion interconnecting the shutter and movement causingportions. The movement causing portion is moved along a lateral surfaceof the disc cartridge to move the shutter portion to open/close therespective openings.

[0023] The disc cartridge according to the present invention alsoincludes a main cartridge body unit and a shutter member. The maincartridge body unit has a recording medium housing section for housingthe disc-shaped recording medium therein, a first wall sectionconstituting the bottom wall of the medium housing section, a secondwall section arranged facing the first wall section, a second openingformed in the second wall section for facing the first opening formed inthe first wall section, a cut-out formed in the peripheral wall of therecording medium housing section and a groove formed in continuation tothe cut-out. The shutter member includes a shutter portion arrangedbetween the first and second wall sections for opening/closing anopening comprised of the first and second openings and a cut-outopening/closing portion arranged in adjacency to the shutter portion forextending from the cut-out to the groove for opening/closing thecut-out. The cut-out opening/closing portion is stepped in shape.

[0024] Other objects and advantages of the present invention will becomeapparent from the following detailed description of the preferredembodiments and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 is a perspective view showing a disc cartridge according tothe present invention.

[0026]FIG. 2 is a perspective view of a disc cartridge according to thepresent invention looking from the bottom side provided with a shuttermechanism and showing both a recording and/or reproducing opening and adriving opening closed by the shutter mechanism.

[0027]FIG. 3 is an exploded perspective view of the disc cartridge.

[0028]FIG. 4 is a plan view of the disc cartridge showing the state ofclosure of the recording and/or reproducing opening and the drivingopening.

[0029]FIG. 5 is a transverse cross-sectional view of the disc cartridge.

[0030]FIG. 6 is a plan view of the disc cartridge showing the openedstate of the recording and/or reproducing opening and the drivingopening.

[0031]FIG. 7, similarly to FIG. 6, is a bottom view of a disc cartridgeshowing the closed state of the recording and/or reproducing opening andthe driving opening.

[0032]FIG. 8 is a perspective view of the disc cartridge showing therecording and/or reproducing opening and the driving opening in theopened state.

[0033]FIG. 9 is an exploded perspective view showing a modification ofthe disc cartridge according to the present invention.

[0034]FIG. 10 is a plan view of the disc cartridge showing the state inwhich the recording and/or reproducing opening and the driving openingare closed.

[0035]FIG. 11 is a longitudinal cross-sectional of the disc cartridge.

[0036]FIG. 12 is a longitudinal cross-sectional view of the disccartridge in which the recording and/or reproducing opening and thedriving opening are opened.

[0037]FIG. 13 is a bottom view of the disc cartridge showing the statein which the recording and/or reproducing opening and the drivingopening are closed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Referring to the drawings, a disc cartridge of the presentinvention will be explained in detail.

[0039] A disc cartridge 1 of the present invention houses an opticaldisc 2 of a recordable type for re-recording the information, such asthe audio or video information, using a disc-shaped recording medium, orhouses a replay-only optical disc 2 having the pre-recorded audio orvideo information. The disc cartridge 1 rotationally houses an opticaldisc 2 in a main cartridge body unit 5 constituted by an upper halfcartridge 3 and a lower half cartridge 4, as shown in FIGS. 1 and 2.

[0040] The optical disc 2, housed in the main cartridge body unit 5, hasa center opening 6, and a hub 7, formed by a plate of a magneticmaterial, such as metal, for closing the center opening 6. The opticaldisc 2 is set on a disc table of a rotational driving mechanism of therecording and/or reproducing apparatus, and has the hub 7 attracted by amagnet provided on the disc table, so that the optical disc 2 will berotated in unison with the disc table. When the optical disc 2 is loadedon the disc table, a centering portion provided at the center of thedisc table is engaged with the center opening 6 to achieve centering sothat the center of rotation of the optical disc 2 will be coincidentwith the center of rotation of the disc table.

[0041] The main cartridge body unit 5, rotationally housing the opticaldisc 2, is combined from an upper half cartridge 3 and a lower halfcartridge 4 abutted and connected to each other, as shown in FIG. 3. Theupper half cartridge 3 and the lower half cartridge 4 are substantiallyrectangular in shape and molded from synthetic resin, as shown in FIG.3.

[0042] The upper half cartridge 3, constituting the main cartridge bodyunit 5, has an upstanding peripheral wall 8 constituting an peripheralwall of the main cartridge body unit 5. The upper half cartridge 3 has afront surface 3 a, as an inserting end of the upper half cartridge 3into the recording and/or reproducing apparatus, presents a continuousarcuate surface. The arcuate front surface 3 a has a mid cut-out 3 binto which is intruded a recording/reproducing mechanism provided on therecording and/or reproducing apparatus. The front surface of the upperhalf cartridge 3 also operates as a front surface of the main cartridgebody unit 5. The opposite lateral surfaces of the main cartridge bodyunit 3 perpendicular to the front surface 3 a of the upper halfcartridge 3 operating as the inserting end into the recording and/orreproducing apparatus are formed as flat surfaces to pen-nit theinserting end into the recording and/or reproducing apparatus to berecognized as such. The disc cartridge can also be distinguished fromthe rectangular disc cartridge widely recognized as the disc cartridge.

[0043] Referring to FIGS. 1 and 2, only the front surface 3 a of theupper half cartridge 3 constituting the front surface of the maincartridge body unit 5 is formed as an arcuate surface, while the lateralsurfaces thereof perpendicular to the front surface 3 a are linear flatsurfaces parallel to each other, so that these lateral surfacers act asinserting guide surfaces at the time of insertion and detachment withrespect to the recording and/or reproducing apparatus to realize stablelateral surfaces of the recording and/or reproducing apparatus.

[0044] The back surface of the main cartridge body unit 5 opposite tothe arcuate front surface 3 a may also be arcuately shaped. In thiscase, the arc of the back surface is preferably larger than the arc ofthe front surface 3 a to permit distinction from the front side of thedisc cartridge 1.

[0045] With the disc cartridge 1, since only the front surface 3 a ofwhich operating as an inserting end into the recording and/orreproducing apparatus, is designed as an arcuate surface, the disccartridge 1 can be reduced in plan size as compared to the optical disc2 housed therein to permit reduction in size of the recording and/orreproducing apparatus employing the disc cartridge 1.

[0046] Referring to FIGS. 2 and 3, the corners on the back side oppositeto the arcuately-shaped front surface 3 a of the upper half cartridge 3are formed with tubular positioning portions 9 engaged by positioningpins on the recording and/or reproducing apparatus. Each of thepositioning portions 9 has its distal end opened and has its proximalend closed by the upper half cartridge 3.

[0047] The lower half cartridge 4, abutted against the upper halfcartridge 3 to constitute the main cartridge body unit 5, is arcuatewith a curvature larger than that of the front surface 3 a of the upperhalf cartridge 3. That is, an arcuate front surface 4 a of the lowerhalf cartridge 4 is arcuate with a radius smaller than that of the frontsurface 3 a of the upper half cartridge 3, as shown in FIG. 3. Theportions of the lower half cartridge 4 other than the front surface 4 aare shaped similarly to the upper half cartridge 3. That is, theopposite lateral sides perpendicular to the front surface 4 a of thelower half cartridge 4 are parallel to each other, with the back surfaceopposite to the front surface 4 a of the lower half cartridge 4 beingformed as planar surfaces.

[0048] On the inner major surface of the lower half cartridge 4 isformed upright an arcuate housing section forming wall 10 constituting acircular disc housing section 11. This housing section forming wall 10has the same radius of curvature as that of the front surface 4 a. Onthe outer perimeter of the lower half cartridge 4 is formed anupstanding peripheral wall 12 abutted against the upstanding peripheralwall 8 constituting the peripheral wall of the main cartridge body unit5 formed upright on the outer rim of the upper half cartridge 3. Insubstantially triangular regions of the back surface side of the lowerhalf cartridge 4 surrounded by the upstanding peripheral wall 12 and thehousing section forming wall 10, there are formed holes 14 into whichare fitted the positioning portions 9 provided on the upper halfcartridge 3.

[0049] Referring to FIGS. 2 and 3, the lower half cartridge 4 is formedwith a recording and/or reproducing opening 15 and a driving opening 16.The recording and/or reproducing opening 15 is adapted for exposing aportion of the signal recording region of the optical disc 2 housed inthe disc housing section 11 to outside across the inner and outer rimsof the disc, and for facing recording and/or reproducing means, such asan optical pickup device, while the driving opening 16 is adapted topermit entrance of the turntable of the rotational driving mechanismprovided on the recording and/or reproducing apparatus. In the presentdisc cartridge 1, the recording and/or reproducing opening 15 is formedin continuation with the driving opening 16.

[0050] Although the recording and/or reproducing opening 15 may beprovided independently of the driving opening 16, there is then provideda partitioning connection portion between the openings 15, 16. If theconnecting portion is provided in this manner, it becomes impossible toshift the recording and/or reproducing mechanism, such as the opticalpickup device, adapted to scan the signal recording region of theoptical disc 2, such that sufficient recording capacity of the opticaldisc 2 cannot be achieved. Therefore, the recording and/or reproducingopening 15 preferably is formed as one with the driving opening 16.

[0051] Referring to FIG. 3, the recording and/or reproducing opening 15is formed substantially as a rectangular opening extending from thevicinity of the mid portion of the disc housing section 11 up to thefront surface 4 a of the lower half cartridge 4. This opening 15,continuing to the driving opening 16, is formed by opening the frontsurface 4 a of the lower half cartridge 4. The driving opening 16 issubstantially circular and is positioned at a mid portion of the dischousing section 11. On the periphery of the inner rim of the drivingopening 16 is formed a disc supporting portion 16 a supporting the rimof the center opening 6 of the optical disc 2 housed in the disc housingsection 11.

[0052] In the main cartridge body unit 5, since the front surface 4 a ofthe lower half cartridge 4 has a curvature larger than the curvature ofthe front surface 3 a of the upper half cartridge 3, the corners of thefront surface of the upper half cartridge 3 are protruded from thecorners on the upper half cartridge 3 when the upper and lower halfcartridges 3, 4 are abutted against each other, as shown in FIG. 4. Theupstanding peripheral wall 8, formed on the portion of the upper halfcartridge 3 protruded from the lower half cartridge 4, is formed to aheight corresponding to the thickness of the main cartridge body unit 5.

[0053] In a lateral surface perpendicular to the front surface of themain cartridge body unit 5 is formed an engagement groove 17 for ashutter opening/closing member, as shown in FIG. 2. When the upper andlower half cartridges 3,4 are abutted against each other, the engagementgroove 17 for a shutter opening/closing member is abutted against agroove 17 a formed in the upstanding peripheral wall 8 of the upper halfcartridge 3 and against a recess 17 b formed in the upstandingperipheral wall 12. When the disc cartridge 1 is inserted into therecording and/or reproducing apparatus, a shutter opening/closing memberconstituting the shutter opening/closing mechanism provided on therecording and/or reproducing apparatus is engaged in the engagementgroove 17 for a shutter opening/closing member for movement therein. Theengagement groove 17 for a shutter opening/closing member is formed witha through-hole 18 into which is protruded part of a lock member 30 aslater explained.

[0054] The front surface 3 a of the upper half cartridge 3 constitutingthe main cartridge body unit 5 is formed with an inner wall 19 havingthe same curvature as that of the front surface 4 a of the lower halfcartridge 4. When the upper and lower half cartridges 3, 4 are abuttedagainst each other, as shown in FIGS. 4 and 5, the inner wall section 19is abutted against the inner surface of the lower half cartridge 4 alongthe outer periphery of the arcuate housing section forming wall 10provided on the lower half cartridge 4. In the inner wall section 19 ofthe upper half cartridge 3 and in the peripheral wall 10 of the lowerhalf cartridge 4 is formed a shutter guide groove 20 for guiding theopening/closure movement of a first shutter member 25 of the shuttermechanism 23, as shown in FIGS. 4 and 5.

[0055] At both corners towards the front surface of the main cartridgebody unit 5 are formed a pair of substantially triangular regionssurrounded by the upstanding peripheral wall 8 and the inner wallsection 19 of the upper half cartridge 3, as shown in FIG. 4. In aregion of the main cartridge body unit 5 provided with the engagementgroove 17 for a shutter opening/closing member provided in the maincartridge body unit 5, there is protruded a supporting shaft 21 forrotationally supporting a lock member 30, as shown in FIG. 4. In theopposite side similar region, there is provided a cover membersupporting protrusion 22 for supporting a cover member 38.

[0056] In the bottom surface of the lower half cartridge 4 constitutingthe main cartridge body unit 5, there is provided a recessed shuttermounting portion 24 in which to mount the shutter mechanism 23 adaptedfor opening/closing the recording and/or reproducing opening 15 and thedriving opening 16, as shown in FIGS. 4 and 5. The shutter mountingportion 24 is formed over an extent through which is slid the shuttermechanism 23 for opening/closing the recording and/or reproducingopening 15 and the driving opening 16.

[0057] The shutter mechanism 23 arranged on the shutter mounting portion24 is made up of a first shutter member 25 for opening/closing therecording and/or reproducing opening 15 and a second shutter member 26for opening/closing the driving opening 16. The first shutter member 25and the second shutter member 26 are arranged in a co-planar relation inthe shutter mounting portion 24. The shutter mechanism 23 may also be sodesigned that the first shutter member 25 mainly opens/closes therecording and/or reproducing opening 15, while the second shutter member26 mainly opens/closes the driving opening 16. That is, the firstshutter member 25 may, for example, be designed so that the secondshutter member 26 is moved to affect a portion of the opening to beopened/closed by the other shutter member to open/close the recordingand/or reproducing opening 15 and the driving opening 16.

[0058] The first shutter member 25 is formed of synthetic resin or metaland is made up of a shutter portion 25 a, formed as a flat plate, amovement guide portion 25 b formed upright on a side of the shutterportion 25 a, and an actuating portion 25 c protruded from one end ofthe movement guide portion 25 b, as shown in FIG. 3. The first shuttermember 25 is mounted on the main cartridge body unit 5, with the shutterportion 25 a being positioned in the shutter mounting portion 24 formedin the lower half cartridge 4 and with the movement guide portion 25 band the actuating portion 25 c being positioned in the shutter guidegroove 20. The shutter portion 25 a is formed as substantiallytrapezoidal shape of a size sufficient to close the recording and/orreproducing opening 15, and carries on its lateral side an arcuateportion of the same curvature as that of the front surface 4 a of thelower half cartridge 4. This shutter portion 25 a is rotated in thedirection indicated by arrows A1 and A2 in FIG. 4, with the center ofthe disc housing section 11 as virtual center, for opening/closing therecording and/or reproducing opening 15.

[0059] The shutter portion 25 a has a side edge opposite to its arcuateportion abutted against the second shutter member 26. The shutterportion 25 a has an overlapping portion 25 e on a side edge abuttedagainst the second shutter member 26. This overlapping portion 25 e isoverlapped with a side of the second shutter member 26. This overlappingportion 25 e may also be provided on the second shutter member 26. Theshutter portion 25 a is provided with a shaft-shaped guide protrusion 27on its major surface, that is on a surface opposite to the shuttermounting portion 24. The shaft-shaped guide protrusion 27 regulates themovement position of the shutter portion 25 a. This shaft-shaped guideprotrusion 27 is provided on the side of the shutter portion 25 aabutted against the second shutter member 26. The shaft-shaped guideprotrusion 27 holds a certain thickness in a portion of the shutterportion 25 a to prevent the first shutter member 25 and the secondshutter member 26 from being shifted into an overlapping relation witheach other at the time of the opening/closure operation.

[0060] The movement guide portion 25 b is formed subsequently uprightwith respect to the shutter portion 25 a for extending along an arcuateportion formed on one side of the shutter portion 25 a. This movementguide portion 25 b is formed in an arcuate shape of the same curvatureas that of the shutter guide groove 20 and is arranged for movementtherein in the direction indicated by arrows A1 and A2 in FIG. 4. Themovement guide portion 25 b is of a length longer than that of thearcuate portion of the shutter portion 25 a so as to reach the vicinityof an end of a shutter guide groove 20 to control the movement so thatthe first shutter member 25 will not be moved in excess of a pre-setdistance in the direction indicated by arrow A2 in FIG. 4. The movementguide portion 25 b is provided with a recess 25 d into which is intrudedthe recording/reproducing mechanism, such as an optical pickup, when theshutter mechanism 23 is opened.

[0061] In the closure position of the shutter mechanism 23, the movementguide portion 25 b closes the cut-out 3 b formed in the front side ofthe main cartridge body unit 5, as shown in FIG. 1. When the shuttermechanism 23 is opened, as shown in FIG. 8, the recess 25 d is moved tothe cut-out 3 b to create an opening in the front side which will permitthe optical disc 2 to be exposed to outside, as shown in FIG. 8. Thatis, the disc cartridge 1 is constructed so that the height H2 in theopened state of the shutter mechanism 23 as shown in FIG. 8 will belower than the height H1 in the closed state of the shutter mechanism23, as shown in FIG. 2. By providing the recess 25 d in the disccartridge 1, the recording/reproducing mechanism provided on therecording and/or reproducing apparatus can be moved towards and awayfrom the optical disc 2. By reducing the distance between the opticaldisc 2 and the recording/reproducing mechanism, it is possible to reducethe thickness of the recording and/or reproducing apparatus employingthe disc cartridge 1.

[0062] The actuating portion 25 c provided on the first shutter member25 is formed as an elastic or resilient member, and is of a thicknessthinner than the movement guide portion 25 b. Similarly to the movementguide portion 25 b, the actuating portion 25 c is arranged within theshutter guide groove 20, with the distal end of the movement guideportion 25 b protruding into the engagement groove 17 for the shutteropening/closing member, as shown in FIG. 4. At the distal end of theactuating portion 25 c, exposed to the engagement groove 17 for theshutter opening/closing member, there is formed an actuating lug 28. Theactuating portion 25 c is pulled into the inside of the engagementgroove 17 for the shutter opening/closing member, by the actuating lug28 engaging with a shutter opening/closure member of the shutteractuating mechanism of the recording and/or reproducing apparatus movedwithin the engagement groove 17 so as to be thrust by the shutteropening/closure member in the direction indicated by arrow C1 in FIG. 4.Partway in the actuating portion 25 c is bored a shutter retentionopening 29. This shutter retention opening 29 is engaged by a lock pawl30 a of a lock member 30 which is arranged in a substantially triangularrecess provided in a region between the upstanding peripheral wall 8 andthe inner wall section 19 of the upper half cartridge 3 and which isrotationally supported by a supporting shaft 21. The opening/closuremovement of the first shutter member 25 is controlled by the lock pawl30 a of the lock member 30 engaging in the shutter retention opening 29of the actuating portion 25 c.

[0063] Since the actuating portion 25 c is formed by an elastic orresilient member, it is able to be moved smoothly, as it is deformed, ina path along the shutter guide groove 20 shaped by the combination of astraight line and a curve, as shown in FIG. 4.

[0064] The lock member 30 includes a lock pawl 30 a, an unlock fever 30b, partially protruded from a through-hole 18 formed in the engagementgroove 17 for the shutter opening/closing member and an elastic member30 c, such as a spring plate, which biases the lock member 30 in thedirection indicated by arrow D in FIG. 4, that is in a direction ofengaging the distal end of the lock pawl 30 a in the shutter retentionopening 29.

[0065] Similarly to the first shutter member 25, the second shuttermember 26 is substantially formed to a sector-shape, from a syntheticresin or metal, to a size sufficient to close the driving opening 16, asshown in FIGS. 3 and 4. The second shutter member 26 is formed with areinforcement 31 along which the guide protrusion 27 of the firstshutter member 25 is abutted and moved. This reinforcement 31 increasesthe contact area with the first shutter member 25 to assure theopening/closing operation of the second shutter member 26. The secondshutter member 26 is provided with an engagement pin 33 near an endthereof for engagement in an engagement opening 32 bored in the lowerhalf cartridge 4. The second shutter member 26 is moved in the directionindicated by arrows B1 and B2 in FIG. 4, about the engagement pin 33 asthe center, for opening/closing the driving opening 16.

[0066] The second shutter member 26 is rotationally biased in thedirection indicated by arrow B2 in FIG. 4 by a torsion coil spring 34arranged in the recess formed in the lower half cartridge 4, as shown inFIG. 4. The torsion coil spring 34 is made up of an annular coil portion34 a, engaged by the engagement pin 33 inserted into the engagementopening 32 so as to be protruded into the substantially triangularrecess in the lower half cartridge 4, an elastic first arm 34 b extendedfrom the coil portion 34 a, and a second arm 34 c longer in length thanthe arm 34 b. The distal end of the second arm 34 c of the torsion coilspring 34 is secured to the lower half cartridge 4, while the first arm34 b compresses against a coil spring thrusting pin 36 inserted througha sector-shaped elongated opening 35 formed in the lower half cartridge4 so as to be protruded into the substantially triangular recess in thelower half cartridge 4. The elongated opening 35 is formed in the lowerhalf cartridge 4 in adjacency to the engagement pin 33 of the secondshutter member 26.

[0067] In the event of the opening/closure operation by the firstshutter member 25 and the second shutter member 26 of the shuttermechanism 23, as shown in FIGS. 4 and 6, the guide protrusion 27 formedon the surface of the shutter mechanism 23 and the reinforcement 31 areshifted. For this reason, the main cartridge body unit 5 is formed witha shutter guide opening 37 for extending over a range of shifting of theguide protrusion 27 and the reinforcement 31 of the lower half cartridge4.

[0068] When the upper half cartridge 3 and the lower half cartridge 4are abutted against and bonded to each other by thermal fusion or withan adhesive to form the main cartridge body unit 5,and the shuttermechanism 23 is arranged on the shutter mounting portion 24 provided onthe main cartridge body unit 5, there is mounted a cover member 38 onthe bottom side of the main cartridge body unit 5, that is on the sideof the lower half cartridge 4 carrying the shutter mounting portion 24.The portion of the cover member 38 in register with the recording and/orreproducing opening 15 and the driving opening 16 is cut out, whilethere is formed an opening 39 at a position in register with thepositioning portion 9 provided on the upper half cartridge 3 forexposing the opening end of the positioning portion 9 to outside. Thecover member 38 holds the shutter mechanism 23 arranged on the shuttermounting portion 24 to prevent the intrusion of dust and dirt into theinside of the main cartridge body unit 5. The cover member 38 issecured, such as with an adhesive, to the main cartridge body unit 5.The disc cartridge 1 is formed in the lower half cartridge 4 with therecording and/or reproducing opening 15 and the driving opening 16, asfirst openings, and with a cut-out in the cover member 38, as a secondopening, to provide the openings operative to expose the center opening6 of the recording region of the optical disc 2 to outside.

[0069] Meanwhile, since the shutter member provided on the routine disccartridge is mounted exteriorly of the main cartridge body unit, and ismoved along the outer surface of the main cartridge body unit, the dustand dirt affixed to the outer surface of the main cartridge body unit isaffixed to the back side of the shutter member to descend into theinside of the disc housing section.

[0070] In the disc cartridge 1 of the present invention, the firstshutter member 25 and the second shutter member 26 are provided in thehousing space defined between an inner wall constituted by the outersurface of the lower half cartridge 4 of the main cartridge body unit 5and the cover member 38 arranged in an overlapping relation on the innerwall to constitute an outer wall, so that there is no risk that the dustand dirt affixed to the outer side of the main cartridge body unit 5 beintruded into the inside of the cartridge housing section 11 to assurereliable protection of the optical disc 2 housed in the main cartridgebody unit 5.

[0071] The portion of the main cartridge body unit 5 where the firstshutter member 25 and the second shutter member 26 are arrangedconstitutes the lower major surface of the main cartridge body unit 5,it is not possible to enlarge the space in which to hold the lower halfcartridge 4 and the cover member 38, or else the main cartridge bodyunit 5 is increased in thickness. In the disc cartridge 1 according tothe present invention, since the movement guide portion 25 b is movedalong the shutter guide groove 20 constituted between the inner wallsection 19 of the upper half cartridge 3 and the peripheral wall 10 ofthe lower half cartridge 4 to cause rotation of the shutter portion 25a, there is no necessity for providing a supporting shaft at the centerof rotation of the shutter portion 25 a, so that the bottom of the maincartridge body unit 5 can be reduced in thickness even if the spacing inwhich to accommodate the shutter members 25, 26 is provided in thebottom of the main cartridge body unit 5, so that there is no fear ofincreasing the thickness of the main cartridge body unit 5.

[0072] In the disc cartridge 1 according to the present invention, thereare provided cartridge supporting portions 40 outwardly of the shuttermounting portion 24,that is at the four corners of the main cartridgebody unit 5 outside the range of movement of the shutter mechanism 23,as shown in FIG. 7. The cartridge supporting portions 40 are supportedby positioning pins provided on the recording and/or reproducingapparatus for setting the positions in the height-wise direction and inthe horizontal direction and height setting pins similarly provided onthe recording and/or reproducing apparatus for setting the positions inthe height-wise direction. The cartridge supporting portions 40 providedat the back side corners of the main cartridge body unit 5 are providedwith positioning portions 9 engaged by the positioning pins, asdescribed above, while the cartridge supporting portions 40 provided atthe front side corners of the main cartridge body unit 5 are left asplain surfaces and are supported by the height setting pins. Inparticular, in the disc cartridge 1 according to the present invention,the front surface of the main cartridge body unit 5 operating as theinserting end into the recording and/or reproducing apparatus is formedas a continuous arcuate surface having a radius larger than that of thearc of the disc housing section 11 provided on the lower half cartridge4, so that the region surrounded by the front surface section of themain cartridge body unit 5 and the disc housing section 11 can beincreased in area. Thus, the cartridge supporting portions 40 of anincreased area are supported by the height setting pins constituting thepositioning supporting mechanism provided on the recording and/orreproducing apparatus, so that the disc cartridge can be reliablypositioned and supported in a stabilized state by the height settingpins provided within the recording and/or reproducing apparatus.

[0073] Meanwhile, the disc cartridge 1 according to the presentinvention delimits a spacing in which to accommodate the shutter members25, 26 in a section for the disc housing section 11 in which toaccommodate the optical disc 2. For constituting this spacing, theportions of the lower half cartridge 4 and the cover member 38 arereduced in thickness. On the other hand, if the delimiting portions ofthe spacing for the shutter members 25, 26 are thrust and deformed, thisspacing is reduced in area so that smooth movement of the shuttermembers 25, 26 is not guaranteed.

[0074] In the disc cartridge 1 of the present invention, there is leftin the front side corners of the main cartridge body unit 5 alarge-sized region which is not the disc housing section 11 nor a regionfor movement of the shutter members 25, 26, this region being used asthe cartridge supporting portion 40. Therefore, if the shutter members25, 26 are adapted for movement along the bottom of the main cartridgebody unit 5, and there is provided a spacing in the bottom of the maincartridge body unit 5 for accommodating the shutter members 25, 26, themain cartridge body unit 5 can be supported with correct positioningalong the height in a stabilized state by the height setting pinsprovided in the recording and/or reproducing apparatus, while smoothmovement of the shutter members 25, 26 is assured.

[0075] Referring to the drawings, the operation of inserting theabove-described disc cartridge 1 into the recording and/or reproducingapparatus and subsequently ejecting the disc cartridge 1 from therecording and/or reproducing apparatus is explained.

[0076] In the non-use state of the disc cartridge 1, that is in thestorage state in which the disc cartridge is not loaded in position inthe recording and/or reproducing apparatus, the first shutter member 25is placed in a position of closing mainly the recording and/orreproducing opening 15, with the second shutter member 26 being at aposition of closing mainly the driving opening 16, as shown in FIG. 4.With the present disc cartridge 1, since the second shutter member 26 isabutted against the first shutter member 25 inhibited as to theopening/closure operation by the lock pawl 30 a of the lock member 30engaging with the shutter retention opening 29, the shutter members 25,26 cannot be moved unless this locking state is released. In the non-usestate, the disc cartridge 1 closes the cut-out 3 b formed in the frontsurface 3 a by the movement guide portion 25 b of the first shuttermember 25, as shown in FIG. 2.

[0077] In the loaded state of the disc cartridge 1 in the recordingand/or reproducing apparatus, the positioning pins for setting thepositions in the horizontal direction and in the height-wise direction,constituting the positioning mechanism provided in the recording and/orreproducing apparatus, are engaged in the engagement holes provided inthe positioning portions 9, while supporting the peripheral portions ofthe positioning portions 9. On the other hand, the height setting pinssupport the flat cartridge supporting portions 40, 40 provided on bothcorners on the front surface of the main cartridge body unit 5, so thatthe disc cartridge 1 is loaded with positioning in the horizontaldirection and in the height-wise direction within the recording and/orreproducing apparatus.

[0078] When the disc cartridge 1 is inserted into the recording and/orreproducing apparatus, a shutter opening/closure member of the shutteractuating mechanism provided on the recording and/or reproducingapparatus is engaged in the engagement groove 17 for the shutteropening/closing member provided on one side of the main cartridge bodyunit 5, so that the unlock lever 30 b of the lock member 30 protrudedinto the engagement groove 17 for the shutter opening/closing member isthrust in the direction indicated by arrow C1 in FIG. 4. Since the lockmember 30 is rotationally supported by the supporting shaft 21, thedistal end of the lock pawl 30 a is rotated in the direction opposite tothat indicated by arrow D in FIG. 4 when the unlock lever 30 b is thrustin the direction indicated by arrow C1 in FIG. 4, so that the distal endof the lock pawl 30 a is disengaged from the shutter retention opening29. When the distal end of the lock pawl 30 a is disengaged from theshutter retention opening 29, the first shutter member 25 is releasedfrom the state of retention.

[0079] When the disc cartridge 1 is inserted further into the recordingand/or reproducing apparatus, the shutter opening/closure member ismoved further in the direction indicated by arrow C1 in FIG. 4 in theengagement groove 17 for the shutter opening/closing member, until theshutter opening/closure member is engaged with the actuating lug 28provided on the actuating portion 25 c of the first shutter member 25.When the actuating lug 28 is engaged in the shutter opening/closuremember, the actuating portion 25 c is pulled into the engagement groove17 for the shutter opening/closing member. If, as shown in FIG. 4, theactuating portion 25 c is pulled into the engagement groove 17 for theshutter opening/closing member, the first shutter member 25 is rotatedto open the recording and/or reproducing opening 15, as shown in FIGS. 6and 8. If, in the disc cartridge 1, the recording and/or reproducingopening 15 is opened, as shown in FIG. 8, the recess 15 d provided inthe movement guide portion 25 b is positioned in the cut-out 3 b intowhich is intruded the recording/reproducing mechanism, such as anoptical pickup, provided on the recording and/or reproducing apparatus,for opening the front surface of the main cartridge body unit 5. Therecording/reproducing mechanism of the recording and/or reproducingapparatus can be approached and intruded into the disc cartridge 1 byopening the cut-out 3 b.

[0080] If the first shutter member 25 is rotated in the direction ofopening the recording and/or reproducing opening 15, the second shuttermember 26 is rotated about the engagement pin 33 as center, in thedirection indicated by arrow B1 in FIG. 6, against the bias of thetorsion coil spring 34, by the guide protrusion 27 whose position ischanged with rotation of the first shutter member 25. When rotated tothe position regulating the rotation of the first shutter member 25, thesecond shutter member 26 opens the driving opening 16, as shown in FIGS.6 and 8.

[0081] When the disc cartridge 1 is introduced into the inside of therecording and/or reproducing apparatus until the recording and/orreproducing opening 15 and the driving opening 16 are opened, the disccartridge 1 is positioned and supported by the positioning mechanism, asdescribed above, and is loaded on the disc table of the rotationaldriving mechanism. If the rotational driving mechanism is run inoperation for rotationally driving the optical disc 2 and for drivingthe recording/reproducing mechanism, such as an optical pickup,information signals are recorded on the optical disc, or the informationsignals recorded on the optical disc are reproduced.

[0082] If, after end of recording of information signals on the opticaldisc 2, or end of reproduction of information signals recorded on theoptical disc, the disc cartridge 1 is to be ejected from the recordingand/or reproducing apparatus, an ejection mechanism is actuated forshifting the shutter opening/closure member of the shutter actuatingmechanism in the direction indicated by arrow C2 in FIG. 6. This thruststhe actuating lug 28 by the shutter opening/closure member to move theactuating lug 28 in the same direction to rotate the first shuttermember 25 in the direction indicated by arrow A2 in FIG. 6 for closingthe recording/reproducing opening 15. If the first shutter member 25 isrotated in the direction of closing the opening 15, the second shuttermember 26 also is rotated, under the bias of the torsion coil spring 34,in the direction indicated by arrow B2 in FIG. 6, to close the drivingopening 16.

[0083] When the first shutter member 25 is restored to the initialposition shown in FIG. 4, the lock pawl 30 a of the lock member 30 isagain engaged in the shutter retention opening 29 formed in theactuating portion 25 c so as to be held in the position of closing therecording and/or reproducing opening 15 as indicated in FIGS. 2 and 4.If the first shutter member 25 is rotated to the position of closing theopening 15, the second shutter member 26 abutted against the firstshutter member 25 also is retained against the bias of the torsion coilspring 34 to close the recording and/or reproducing opening 15 and thedriving opening 16.

[0084] Meanwhile, the shutter mechanism 23 provided in the disccartridge 1 according to the present invention is configured foropening/closing the recording and/or reproducing opening 15 and thedriving opening 16 by the first and second shutter members 25, 26. Thefirst and second shutter members 25, 26 are configured for beingoverlapped with each other to preclude a gap otherwise produced in theabutting portion when the first and second shutter members 25, 26 havebeen rotated to the position of closing the opening 15 and the drivingopening 16. In the illustrated embodiment, a step 25 a is provided onone side of the first shutter member 25, as shown in FIG. 8, so that,when the first and second shutter members 25, 26 have been rotated tothe position of closing the openings 15, 16, the second shutter member26 is partially overlapped on a step 25 a to close the openings 15, 16completely, as shown in FIG. 2. Since the openings 15, 16 are closed asthe first and second shutter members 25, 26 are partially overlappedwith each other, it is possible to prevent dust and dirt from enteringthe inside of the main cartridge body unit 5 via the abutting portionsof the first and second shutter members 25, 26.

[0085] Since the recording and/or reproducing opening 15 and the drivingopening 16 in the present disc cartridge 1 are opened and closed by thefirst and second shutter members 25, 26 which are split and are rotatedalong the bottom side major surface of the main cartridge body unit 5,it is possible to constitute the openings 15, 16 with sizes larger thanthe size of the main cartridge body unit 5. That is, since the recordingand/or reproducing opening 15 and the driving opening 16 can be largerin size than the openings provided on the conventional disc cartridgeopened and closed by a shutter member movable along a lateral side ofthe main cartridge body portion, it is possible to use a recordingmedium of the recording and/or reproducing apparatus having alarge-sized optical pickup device having plural object lenses.

[0086] Moreover, since the recording and/or reproducing opening 15 andthe driving opening 16 are provided for extending along the direction ofinsertion of the disc cartridge 1 into the recording and/or reproducingapparatus, the disc cartridge can be easily loaded on the recordingand/or reproducing apparatus in which the rotational driving mechanismand recording and/or reproducing means, such as an optical pickupdevice, are arranged in tandem, for extending along the disc cartridgeinserting direction.

[0087] Also, with the disc cartridge 1 of the present invention, thefirst and second shutter members 25, 26 are opened/closed in unison bythe actuating portion 25 c being actuated in the direction of beinginserted into and detached from the recording and/or reproducingapparatus. Thus, with the recording and/or reproducing apparatus, it isonly sufficient if a bar-shaped pin, for example, is provided in adirection towards the entrance/exit opening, as a shutteropening/closure member adapted for opening the shutter mechanism 23 ofthe disc cartridge 1, thus simplifying the loading mechanism for thedisc cartridge 1.

[0088] Since the shutter mechanism 23 in the disc cartridge 1 of thepresent invention is opened or closed by the actuating portion 25 cprovided for extending along the lateral side of the main cartridge bodyunit 5, there is no limitation imposed on the shape of the front side ofthe main cartridge body unit 5 by the shutter mechanism 23. Although thefront side of the main cartridge body unit 5 is arcuate in the abovedescription, the front side of the main cartridge body unit 5 may beshaped freely insofar as it is not collided against the optical disc 2housed therein.

[0089] In the disc cartridge 1 according to the present invention, theshutter portion 25 a, movement guide portion 25 b and the actuatingportion 25 c of the first shutter member 25 may be formed as one fromthe same material, or from different materials, and subsequentlycombined together. That is, the shutter portion 25 a, movement guideportion 25 b and the actuating portion 25 c of the first shutter member25 may be formed of suitable materials depending on the physicalproperties, such as resiliency or durability required of thesecomponents.

[0090] Although the recording and/or reproducing opening 15 and thedriving opening 16 are formed in the lower half cartridge 4, it is alsopossible to form similar openings in the upper half cartridge 3 and toprovide the upper half cartridge 3 with the shutter mechanism 23.

[0091] A modification of the disc cartridge according to the presentinvention is now explained.

[0092] Referring to FIG. 9, a disc cartridge 50 houses an optical disc51 for rotation in a main cartridge body unit 54 constituted by an upperhalf cartridge 52 and a lower half cartridge 53.

[0093] The optical disc 51, housed in the main cartridge body unit 54,has a center opening 55 and a hub 51 a formed of a magnetic material,such as a metal plate, for closing the center opening 55. The opticaldisc 51 is set on a disc table of a rotational driving mechanism of therecording and/or reproducing apparatus and has a hub 51 a attracted by amagnet provided on the disc table so that the optical disc 51 will berotated in unison with the disc table. When the optical disc 55 isloaded on the disc table, a centering portion provided at the center ofthe disc table is engaged with the center opening 55 to achievecentering in which the center of rotation of the optical disc 51 iscoincident with the center of rotation of the disc table.

[0094] The main cartridge body unit 54, rotationally housing the opticaldisc 51, is combined from an upper half cartridge 52 and a lower halfcartridge 53 abutted and connected to each other. The upper halfcartridge 3 and the lower half cartridge 4 are substantially rectangularin shape and molded from synthetic resin, as shown in FIG. 9.

[0095] The upper half cartridge 52, constituting the main cartridge bodyunit 54, has an upstanding peripheral wall 8 constituting a peripheralwall of the main cartridge body unit 54. The upper half cartridge 52 hasa front surface 52 a, as an inserting end of the upper half cartridge 52into the recording and/or reproducing apparatus, presents a continuousarcuate surface. The front surface 52 a of the upper half cartridge 52also operates as a front surface of the main cartridge body unit 54. Theopposite lateral surfaces of the main cartridge body unit 54perpendicular to the front surface 52 a of the upper half cartridge 52operating as the inserting end into the recording and/or reproducingapparatus are formed as flat surfaces to permit the inserting end intothe recording and/or reproducing apparatus to be recognized as such. Thedisc cartridge can also be distinguished from the rectangular disccartridge, having flat lateral sides, widely recognized as the disccartridge.

[0096] Since only the front surface 52 a of the upper half cartridge 52constituting the front surface of the main cartridge body unit 54 isformed as an arcuate surface, while the lateral surfaces thereofperpendicular to the front surface 52 a are linear flat surfacesparallel to each other, these lateral surfacers act as inserting guidesurfaces at the time of insertion and detachment with respect to therecording and/or reproducing apparatus to realize stable lateralsurfaces of the recording and/or reproducing apparatus.

[0097] With the disc cartridge 50, only the front surface 52 a thereofoperating as an inserting end into the recording and/or reproducingapparatus is designed as an arcuate surface, the disc cartridge 50 canbe reduced in plan size as compared to the optical disc 52 housedtherein to permit reduction in size of the recording and/or reproducingapparatus employing the disc cartridge 50.

[0098] The corners on the back side opposite to the arcuately-shapedfront surface 52 a of the upper half cartridge 52 are formed withtubular positioning portions 57 engaged by positioning pins constitutingpositioning means provided on the recording and/or reproducingapparatus. Each of the positioning portions 57 has its distal end openedand has its proximal end closed by the upper half cartridge 52.

[0099] The lower half cartridge 53, abutted against the upper halfcartridge 52 to constitute the main cartridge body unit 54, is arcuatewith a radius smaller than that of the front surface 53 a of the upperhalf cartridge 52. That is, an arcuate front surface 53 a of the lowerhalf cartridge 53 is arcuate with a radius smaller than that of thefront surface 52 a of the upper half cartridge 52, as shown in FIG. 9.The portions of the lower half cartridge 53 other than the front surface53 a are shaped similarly to the upper half cartridge 52. That is, theopposite lateral sides perpendicular to the front surface 53 a of thelower half cartridge 53 is arcuate with a radius smaller than that ofthe front surface 53 a of the lower half cartridge 53, as shown in FIG.9. The portions of the lower half cartridge 53 other than the frontsurface 53 a are shaped similarly to the upper half cartridge 52. Thatis, the opposite lateral sides perpendicular to the front surface 53 aof the lower half cartridge 53 are parallel to each other, with the backsurface opposite to the front surface 53 a being formed as planarsurfaces.

[0100] On the inner major surface of the lower half cartridge 53 isformed upright an arcuate housing section forming wall 58 constituting acircular disc housing section 59. This housing section forming wall 58has the same radius of curvature as that of the front surface 53 a. Onthe outer perimeter of the lower half cartridge 53 is formed anupstanding peripheral wall 60 abutted against the upstanding peripheralwall 56 constituting the peripheral wall of the main cartridge body unit54 formed upright on the outer rim of the upper half cartridge 52. Insubstantially triangular regions of the back surface side of the lowerhalf cartridge 53 surrounded by the upstanding peripheral wall 60 andthe housing section forming wall 58, there are formed holes 61 intowhich are fitted the positioning portions 57 provided on the upper halfcartridge 52.

[0101] Referring to FIG. 9, the lower half cartridge 53 is formed with arecording and/or reproducing opening 62 and a driving opening 63. Therecording and/or reproducing opening 62 is adapted for exposing aportion of the signal recording region of the optical disc 51 housed inthe disc housing section 59 to outside across the inner and outer rimsof the disc, and for facing recording and/or reproducing means, such asan optical pickup device, while the driving opening 63 is adapted topermit entrance of a turntable of the rotational driving mechanismprovided on the recording and/or reproducing apparatus. In the presentdisc cartridge 50, the recording and/or reproducing opening 62 is formedin continuation with the driving opening 63.

[0102] Referring to FIG. 9, the recording and/or reproducing opening 62is formed substantially as a rectangular opening extending from thevicinity of the mid portion of the disc housing section 59 up to thefront surface 53 a of the lower half cartridge 53. This opening 52,continuing to the driving opening 63, is formed by opening the frontsurface 53 a of the lower half cartridge 53. The driving opening 63 issubstantially circular and is positioned at a mid portion of the dischousing section 59. On the periphery of the inner rim of the drivingopening 63 is formed a disc supporting portion 63 a supporting the rimof the center opening 55 of the optical disc 51 housed in the dischousing section 59.

[0103] In the main cartridge body unit 54, since the front surface 53 aof the lower half cartridge 53 has a curvature larger than the curvatureof the front surface 52 a of the lower half cartridge 52, the corners ofthe front surface of the upper half cartridge 52 are protruded from thecorners on the upper half cartridge 52 when the upper and lower halfcartridges 52, 53 are abutted against each other, as shown in FIG. 10.The upstanding peripheral wall 56, formed on the portion of the upperhalf cartridge 52 protruded from the lower half cartridge 53, is formedto a height corresponding to the thickness of the main cartridge bodyunit 54.

[0104] In a lateral surface perpendicular to the front surface of themain cartridge body unit 54 is formed an engagement groove 64 for ashutter opening/closing member. When the upper and lower half cartridges52, 53 are abutted against each other, the engagement groove 64 for ashutter opening/closing member is abutted against a groove 64 a formedin the upstanding peripheral wall 56 of the upper half cartridge 52 andagainst a recess 64 b formed in the upstanding peripheral wall 60 on thelower half cartridge 53. When the disc cartridge 50 is inserted into therecording and/or reproducing apparatus, a shutter opening/closing memberconstituting the shutter opening/closing mechanism provided on therecording and/or reproducing apparatus is engaged in the engagementgroove 64 for a shutter opening/closing member for movement therein. Theengagement groove 64 for a shutter opening/closing member is formed witha through-hole 65 into which is protruded part of a lock member 77 aslater explained.

[0105] The front surface 52 a of the upper half cartridge 52constituting the main cartridge body unit 54 is formed with an innerwall 66 having the same curvature as that of the front surface 53 a ofthe lower half cartridge 53. When the upper and lower half cartridges52, 53 are abutted against each other, as shown in FIGS. 10 and 11, theinner wall section 66 is abutted against the inner surface of the lowerhalf cartridge 53 along the outer periphery of the arcuate housingsection forming wall 58 provided on the lower half cartridge 53. In theinner wall section 66 of the upper half cartridge 52 and in housingsection forming wall 58 of the lower half cartridge 53 is formed ashutter guide groove 67 for guiding the opening/closure movement of afirst shutter member 71 of the shutter mechanism 69, as shown in FIGS.10 and 11.

[0106] At both corners towards the front surface of the main cartridgebody unit 54 are formed a pair of substantially triangular regionssurrounded by the upstanding peripheral wall 56 and the inner wallsection 66 of the upper half cartridge 52, as shown in FIG. 10. In aregion of the main cartridge body unit 54 provided with the engagementgroove 64 for a shutter opening/closing member provided in the maincartridge body unit 54, there is protruded a supporting shaft 68 forrotationally supporting the lock member 77, as shown in FIG. 10.

[0107] In the bottom surface of the lower half cartridge 53 constitutingthe main cartridge body unit 54, there is provided a recessed shuttermounting portion 70 in which to mount the shutter mechanism 69 adaptedfor opening/closing the recording and/or reproducing opening 62 and thedriving opening 63. The shutter mounting portion 70 is formed over anextent through which is slid the shutter mechanism 69 foropening/closing the recording and/or reproducing opening 62 and thedriving opening 63.

[0108] The shutter mechanism 69 arranged on the shutter mounting portion70 is made up of a first shutter member 71 for opening/closing therecording and/or reproducing opening 62 and a second shutter member 72for opening/closing the driving opening 63. The first shutter member 71and the second shutter member 72 are arranged with an overlap at theends operating as the center of rotation, with other portions of thefirst and second shutter members 71, 72 being arranged on the co-planarplane in the shutter mounting portion 70.

[0109] The first shutter member 71 is formed of synthetic resin or metaland is made up of a shutter portion 71 a, formed as a flat plate, amovement guide portion 71 b formed upright on a side of the shutterportion 71 a, and an actuating portion 71 c protruded from one end ofthe movement guide portion 71 b, as shown in FIG. 9. The first shuttermember 71 is mounted on the main cartridge body unit 54, with theshutter portion shutter portion 71 a being positioned in the shuttermounting portion 70 formed in the lower half cartridge 53 and with themovement guide portion 71 b and the actuating portion 71 c beingpositioned in the shutter guide groove 67. The shutter portion shutterportion 71 a is formed as substantially trapezoidal shape of a sizesufficient to close the recording and/or reproducing opening 62, andcarries on its lateral side an arcuate portion of the same curvature asthat of the front surface 53 a of the lower half cartridge 53. Thisshutter portion shutter portion 71 a is rotated in the directionindicated by arrows Engagement groove 17 for a shutter opening/closingmember and E2 in FIG. 10 with the center of the disc housing section 59as virtual center, for opening/closing the recording and/or reproducingopening 62. The shutter portion 71 a is abutted against the secondshutter member 72 along the arcuate-shaped lateral surface.

[0110] The movement guide portion 71 b is formed subsequently uprightwith respect to the shutter portion shutter portion 71 a for extendingalong an arcuate portion formed on one side of the shutter portionshutter portion 71 a. This movement guide portion 71 b is formed in anarcuate shape of the same radius of curvature as that of the shutterguide groove 67 and is arranged for movement therein in the directionindicated by arrows Engagement groove 17 for a shutter opening/closingmember and E2 in FIG. 10. The movement guide portion 71 b is of a lengthlonger than the arcuate portion of the shutter portion shutter portion71 a to reach the vicinity of an end of a shutter guide groove 67 tocontrol the movement of the first shutter member 71 so that the latterwill not be moved in excess of a pre-set distance in the directionindicated by arrow E2 in FIG. 10. The movement guide portion 71 b isprovided with a recess 71 d into which is intruded therecording/reproducing mechanism, such as an optical pickup, when theshutter mechanism 69 is opened.

[0111] In the closure position of the shutter mechanism 69, the movementguide portion 71 b closes the cut-out 3 b formed in the front side ofthe main cartridge body unit 54. When the shutter mechanism 69 isopened, the recess 71 d is moved to the cutout 3 b to create an openingin the front side which will permit the optical disc 51 to be exposed tooutside. By providing the recess 71 d in the disc cartridge 50, therecording/reproducing mechanism provided on the recording and/orreproducing apparatus can be moved towards the optical disc 51. Byreducing the distance between the optical disc 51 and therecording/reproducing mechanism in this manner, it is possible to reducethe thickness of the recording and/or reproducing apparatus.

[0112] The actuating portion 71 c provided on the first shutter member71 is formed as an elastic or resilient member, and is of a thicknessthinner than the movement guide portion 71 b. Similarly to the movementguide portion 71 b, the actuating portion 71 c is arranged within theshutter guide groove 67, with the distal end of the movement guideportion protruding into the engagement groove 64 for a shutteropening/closing member, as shown in FIG. 10. At the distal end of theactuating portion 71 c, exposed to the engagement groove 64 for ashutter opening/closing member, there is formed an actuating lug 75. Theactuating portion 71 c is pulled into the inside of the engagementgroove 64 for a shutter opening/closing member, by the actuating lug 75engaging with shutter opening/closure member of the shutter actuatingmechanism provided on the recording and/or reproducing apparatus so asto be thrust by the shutter opening/closure member in the directionindicated by arrow G1 in FIG. 10, with the actuating lug 75 being thenmoved within the engagement groove 64 for a shutter opening/closingmember. Partway in the actuating portion 71 c is bored a shutterretention opening 76. This shutter retention opening 76 is engaged by alock pawl 77 a of the lock member 77 which is arranged in asubstantially triangular recess provided in a region between theupstanding peripheral wall 56 and the inner wall section 66 of the upperhalf cartridge 52 and which is rotationally supported by a supportingshaft 68. The opening/closure movement of the first shutter member 71 iscontrolled by the lock pawl 77 a of the lock member 77 engaging in theshutter retention opening 76 of the actuating portion 71 c.

[0113] The lock member 77 includes a lock pawl 77 a, an unlock lever 77b, partially protruded from a through-hole 65 formed in the engagementgroove 64 for the shutter opening/closing member, and an elastic member77 c, such as a spring plate, which biases the lock member 77 in thedirection indicated by arrow H in FIG. 10, that is in a direction ofengaging the distal end of the lock pawl 77 a in the shutter retentionopening 76.

[0114] The second shutter member 72 is formed of, for example, syntheticresin or metallic material, and is of a width sufficient to close thedriving opening 63. The second shutter member 72 includes two pins 78 onits major surface that are fitted into an operating guide groove 80 forguiding the trajectory of the opening/closure movement to control thetrajectory of the shutter opening/closure operation.

[0115] The shutter mechanism 69 is configured so that the first shuttermember 71 and the second shutter member 72 are fitted in an elongatedopening for rotation 74 provided in the second shutter member 72 so thatthe operation of one of the shutter members occurring in associationwith that of the other member for opening or closing the openings. Also,in the shutter mechanism 69, the portion of the second shutter member 72formed with an opening for rotation 76 is stepped so that the thus, withthe shutter mechanism 69, the stepped portion of the second shuttermember 72 is placed within a sliding portion 79 in which the shuttermounting portion 70 is arranged as a recess.

[0116] When the upper half cartridge 52 and the lower half cartridge 53are abutted against and bonded to each other by thermal fusion or withan adhesive to form the main cartridge body unit 54, and the shuttermechanism 69 is arranged on the shutter mounting portion 70 provided onthe main cartridge body unit 54, there is mounted a cover member 81 onthe bottom side of the main cartridge body unit 54, that is on the sideof the lower half cartridge 53 carrying the shutter mounting portion 70.The portion of the cover member 81 in register with the recording and/orreproducing opening 62 and the driving opening 63 is cut out, whilethere is formed a cut-out 81 a at a position in register with thepositioning portion 57 provided on the upper half cartridge 52 forexposing the opening end of the positioning portion 57 to outside. Thecover member 81 holds the shutter mechanism 69 arranged on the shuttermounting portion 70 to prevent the intrusion of dust and dirt into theinside of the main cartridge body unit 54. The cover member 81 issecured, such as with an adhesive, to the main cartridge body unit 54.The disc cartridge 50 is formed in the lower half cartridge 53 with therecording and/or reproducing opening 62 and the driving opening 63, asfirst openings, and with a cut-out in the cover member 81, as a secondopening, to provide the openings operative to expose the center opening55 of the recording region of the optical disc 51 to outside.

[0117] Meanwhile, since the shutter member provided on the routine disccartridge is mounted exteriorly of the main cartridge body unit, and ismoved along the outer surface of the main cartridge body unit, the dustand dirt affixed to the outer surface of the main cartridge body unit isaffixed to the back side of the shutter member at the time of theshutter member to descend into the inside of the disc housing section.

[0118] In the disc cartridge 1 of the present invention, the firstshutter member 71 and the second shutter member 72 are provided in thehousing space defined between the inner wall constituted by the outersurface of the lower half cartridge 53 of the main cartridge body unit54 and the cover member 81 arranged in an overlapping relation on theinner wall to constitute the outer wall, so that there is no risk thatthe dust and dirt affixed to the outer side of the main cartridge bodyunit 5 be intruded into the inside of the cartridge housing section 59.That is, the first and second shutter members 71, 72 are not moved alongthe outer sides of the main cartridge body unit 54 where dust and dirtare liable to be deposited, but are moved within the inside of the maincartridge body unit 54, so that dust anddirt affixed to the outersurface of the main cartridge body unit 54 are positively prevented fromentering the inside of the cartridge housing section 59 to assurereliable protection of the optical disc 51 housed in the main cartridgebody unit 54.

[0119] In the disc cartridge 50 of the present invention, a cartridgesupporting portion 82 supported by a positioning pin constituting apositioning mechanism provided on the recording and/or reproducingapparatus for setting the position along the height and in thehorizontal direction and by a height setting pin setting the position inthe height-wise direction is provided at each of four corners of themain cartridge body unit 54 outwardly of the shutter mounting portion70, that is outside the range of movement of the shutter mechanism 69,as shown in FIG. 13. The cartridge supporting portions 82, provided onthe back side corners of the main cartridge body unit 54, are providedwith positioning portions 57 engaged by the positioning pins, while thecartridge supporting portions 82 provided at the front side corners ofthe main cartridge body unit 54 are left as plain surfaces and aresupported by the height setting pins. In particular, in the disccartridge 50 according to the present invention, the front surface ofthe main cartridge body unit 54 operating as the inserting end into therecording and/or reproducing apparatus is formed as a continuous arcuatesurface having a radius larger than the arc of the arc of the dischousing section 59 provided on the lower half cartridge 4, so that theregion surrounded by the front surface section of the main cartridgebody unit 54 and the disc housing section 59 can be increased in area.Thus, the cartridge supporting portions 82 of an increased area aresupported by the height setting pins constituting the positioningsupporting mechanism provided on the recording and/or reproducingapparatus, so that the disc cartridge can be reliably positioned andsupported in a stabilized state by the height setting pins providedwithin the recording and/or reproducing apparatus.

[0120] In the disc cartridge 50 of the present invention, there is leftin the front side corners of the main cartridge body unit 54 alarge-sized region which is not the disc housing section 59 nor a regionfor movement of the shutter members 71, 72, this region being used asthe cartridge supporting portion 82. Therefore, if the shutter members71, 72 are adapted for movement along the bottom of the main cartridgebody unit 54, and there is provided a spacing in the bottom of the maincartridge body unit 54 for accommodating the shutter members 71, 72, themain cartridge body unit 54 can be supported with correct positioningalong the height in a stabilized state by the height setting pinsprovided in the recording and/or reproducing apparatus while smoothmovement of the shutter members 71, 72 is assured.

[0121] Referring to the drawings, the operation of inserting theabove-described disc cartridge 50 into the recording and/or reproducingapparatus and subsequently ejecting the disc cartridge 50 from therecording and/or reproducing apparatus is explained.

[0122] In the non-use state of the disc cartridge 50, that is in thestorage state in which the disc cartridge is not loaded in position inthe recording and/or reproducing apparatus, the first shutter member 71is placed in a position of closing mainly the recording and/orreproducing opening 62, with the second shutter member 72 being at aposition of closing mainly the driving opening 63, as shown in FIG. 10.With the present disc cartridge 50, since the second shutter member 72is abutted against the first shutter members 71, inhibited from theopening/closure movement by the lock pawl 77 a of the lock member 77engaging with the shutter retention opening 76, the first and secondshutter members71, 72 are inhibited from movement unless this lockedstate is released.

[0123] When the disc cartridge 50 is loaded on the recording and/orreproducing apparatus, the positioning pins for setting the loadingposition in the horizontal direction and in the height-wise direction,constituting a positioning mechanism arranged in the recording and/orreproducing apparatus, are engaged in the engagement openings providedin the positioning portion 57, while supporting the peripheral portionof the positioning portion 57. In addition, the height setting pinssupport the flat cartridge supporting portions 82, 82 provided at bothcorners on the front side of the main cartridge body unit 54, wherebythe disc cartridge 50 is loaded in position in the horizontal directionand in the height-wise direction in the recording and/or reproducingapparatus.

[0124] In the non-use state of the disc cartridge 50, that is in thestorage state in which the disc cartridge is not loaded in position inthe recording and/or reproducing apparatus, the first shutter member 71is placed in a position of closing mainly the recording and/orreproducing opening 62, with the second shutter member 72 being at aposition of closing mainly the driving opening 63, as shown in FIG. 10.With the present disc cartridge 50, the first and second shutter members71, 72 are inhibited from movement unless a locked state is released. Itis noted that the lock pawl 77 a of the lock member 77 is engaged withthe shutter retention opening 76 to inhibit the first shutter member 71from performing an opening/closure movement.

[0125] When the disc cartridge 50 is inserted into the recording and/orreproducing apparatus, the positioning pins for setting the loadingposition in the horizontal direction and in the height-wise direction,constituting a positioning mechanism arranged in the recording and/orreproducing apparatus, are engaged in the engagement opening provided inthe positioning portion 57, while supporting the peripheral portion ofthe positioning portion 57. In addition, the height setting pins supportthe flat cartridge supporting portions 82, 82 provided at both cornerson the front side of the main cartridge body unit 54, whereby the disccartridge 50 is loaded in position in the horizontal direction and inthe height-wise direction in the recording and/or reproducing apparatus.

[0126] The shutter opening/closure member of the shutter actuatingmechanism provided on the recording and/or reproducing apparatus isengaged in the engagement groove 64 for a shutter opening/closing memberprovided on one side of the main cartridge body unit 54, so that theunlock lever 77 b of the lock member 77 protruded into the engagementgroove 64 for a shutter opening/closing member is thrust in thedirection indicated by arrow G1 in FIG. 10. Since the lock member 77 isrotationally supported by the supporting shaft 68, the distal end of thelock pawl 77 a is rotated in the direction opposite to that indicated byarrow H in FIG. 7, when the unlock lever 77 b is thrust in the directionindicated by arrow G1 in FIG. 10, so that the distal end of the lockpawl 77 a is disengaged from the shutter retention opening 76. When thedistal end of the lock pawl 30 a is disengaged from the shutterretention opening 76, the first shutter member 71 is released from thestate of retention.

[0127] When the disc cartridge 50 is inserted further into the recordingand/or reproducing apparatus, the shutter opening/closure member ismoved further in the direction indicated by arrow G1 in FIG. 10 in theengagement groove 64 for the shutter opening/closing member, until theshutter opening/closure member is engaged with the actuating lug 75provided on the actuating portion 71 c of the first shutter member 71protruded into the engagement groove 64 for a shutter opening/closingmember. When the actuating lug 75 is engaged in the shutteropening/closure member, the actuating portion 71 c is pulled into theengagement groove 64 for the shutter opening/closing member. If, asshown in FIG. 12, the actuating portion 71 c is pulled into theengagement groove 64 for a shutter opening/closing member, the shuttermember shutter portion shutter portion 71 a and the movement guideportion 71 b are rotated to open the recording and/or reproducingopening 62, as shown in FIG. 12.

[0128] In the disc cartridge 50, the first shutter member 71 and thesecond shutter member 72 are rotated in the direction indicated by arrowF1 in FIG. 7, in association with the movement of the supporting shaftfor rotation 73 fitted in the elongated opening for rotation 74 to openthe driving opening 63.

[0129] If the disc cartridge 50 is inserted into the inside of therecording and/or reproducing apparatus up to a position of opening therecording and/or reproducing opening 62 and the driving opening 63, thedisc cartridge 50 is loaded on the cartridge loading section within therecording and/or reproducing apparatus, as it is positioned andsupported by the positioning mechanism, until the disc cartridge isloaded on the disc table of the rotational driving mechanism. Therotating driving mechanism then is driven for rotationally driving theoptical disc 51, while the recording/reproducing mechanism, such as anoptical pickup, is driven for recording information signals on theoptical disc 51 or reproducing the information signals recorded on theoptical disc 51.

[0130] If, after the recording of the information signals on the opticaldisc 51, or after the end of reproduction of the information signalsrecorded on the optical disc 51, the disc cartridge 50 is to be ejectedfrom the recording and/or reproducing apparatus, an ejection mechanismis actuated to cause movement of the shutter opening/closure member ofthe shutter actuating mechanism in the direction indicated by arrow G2in FIG. 12. This causes the actuating lug 75 to be thrust by the shutteropening/closure member and moved in the same direction to cause rotationof the first shutter member 71 in the direction indicated by arrow E2 inFIG. 12 to close the opening 62. If the first shutter member 71 isrotated in the direction of closing the first shutter member 62, thesecond shutter member 72 also is pulled by the supporting shaft 73fitted in the elongated opening for rotation 74 so as to be rotated inassociation with the operation of the supporting shaft 73 in thedirection indicated by arrow F2 in FIG. 12 to close the driving opening63.

[0131] When the first shutter member 71 is returned to the initialposition shown in FIG. 10, the lock pawl 77 a of the lock member 77 isagain engaged in the shutter retention opening 76 formed in theactuating portion 71 c so that the first shutter member 71 is held inthe position of FIG. 10 to close the recording and/or reproducingopening 62. When the first shutter member 71 has been rotated to theposition of closing the opening 62, the second shutter member 72,rotated in unison with the first shutter member 71, is also held in theposition of closing the driving opening 63 to close both the recordingand/or reproducing 62 and the driving opening 63.

What is claimed is:
 1. A disc cartridge for housing a disc-shapedrecording medium adapted for recording information signals thereon,comprising: a main cartridge body unit rotationally housing thedisc-shaped recording medium, said main cartridge body unit includingfirst and second wall sections at a portion thereof facing the majorsurface of the disc-shaped recording medium, said first and second wallsections facing each other at a pre-set spacing from each other, arecording and/or reproducing opening facing said first and second wallsections for exposing a portion of a signal recording region of thedisc-shaped recording medium across the inner and outer rims of thedisc-shaped recording medium to outside, and a driving opening facingsaid first and second wall sections for exposing the center portion ofthe disc-shaped recording medium to outside; and first and secondshutter members for opening/closing said recording and/or reproducingopening and the driving opening; said first and second shutter membersbeing supported by said main cartridge body unit so as to be movedbetween said first and second wall sections.
 2. The disc cartridgeaccording to claim 1 wherein said first and second shutter membersinclude overlapping portions on respective sides thereof, saidoverlapping portions being overlapped with each other when the first andsecond shutter members have been moved to the position of closing saidrecording and/or reproducing opening and the driving opening.
 3. Thedisc cartridge according to claim 1 wherein said first shutter member issupported so that its one end will be moved along a position close tothe outer periphery of a circular medium housing section formed on saidmain cartridge body unit for rotationally housing said disc-shapedrecording medium therein; and wherein said second shutter member issupported by said main cartridge body unit by having its portion engagedand held by an engagement holding portion provided on said first shuttermember, so that the second shutter member will be rotated in associationwith rotation of said first shutter member, said second shutter memberbeing intimately contacted with a side of said first shutter member toclose the recording and/or reproducing opening when the first shuttermember has been moved to a first position of closing said recordingand/or reproducing opening, said second shutter member being rotatedwith said first shutter member to a position opening said recordingand/or reproducing opening when the first shutter member has beenrotated to the second position of opening the recording and/orreproducing opening.
 4. The disc cartridge according to claim 3 whereinan arcuate guide groove is formed for extending along the outer rim ofthe circular medium housing section, said guide groove being engaged byan arcuate upstanding section formed on one side of said first shuttermember, said upstanding section being moved within said guide groove tocause rotation of said first shutter member.
 5. The disc cartridgeaccording to claim 3 wherein said first shutter member includes ashutter portion for opening/closing the recording and/or reproducingopening and the driving opening, a movement causing portion for causingthe movement of the shutter portion and a connecting portioninterconnecting said shutter portion and said movement causing portion,said movement causing portion being moved along a side of said disccartridge to cause movement of the shutter portion.
 6. The disccartridge according to claim 5 wherein an arcuate guide groove is formedfor extending along the outer peripheral surface of said circular mediumhousing section, a linear guide groove being formed along a lateral sideof said main cartridge body unit so as to be smoothly continuing to saidarcuate guide groove; there being an arcuate upstanding portion towardsone side of said first shutter member, said upstanding portion beingconnected to said movement causing portion through said connectingportion, said shutter member being supported by said main cartridge bodyunit so that the arcuate upstanding portion will be moved in saidarcuate guide groove, said movement causing portion will be moved insaid linear guide groove and said connecting portion will be moved insaid arcuate guide groove and in said linear guide groove.
 7. The disccartridge according to claim 5 wherein said movement causing portion isflexible.
 8. The disc cartridge according to claim 5 further comprising:a lock mechanism inhibiting movement of the shutter portion of the firstshutter member lying at a position of closing said recording and/orreproducing opening and the driving opening.
 9. The disc cartridgeaccording to claim 8 further comprising: means for releasing theinhibition of movement of said shutter portion by said lock mechanism,said releasing means being provided on a lateral surface of said maincartridge body unit along which is moved said movement causing portion.10. The disc cartridge according to claim 9 wherein the means forreleasing the inhibition of movement of said shutter portion by saidlock mechanism is a first protrusion that appears and disappears on alateral surface of said main cartridge body unit, said movement causingportion is a second protrusion moved along a lateral surface of saidmain cartridge body unit and wherein said first and second protrusionsare positioned in a recessed groove formed along a lateral surface ofsaid main cartridge body unit.
 11. The disc cartridge according to claim10 wherein said first and second protrusions are arranged in this orderwhen looking from the disc cartridge inserting side into the recordingand/or reproducing apparatus.
 12. A disc cartridge for housing adisc-shaped recording medium adapted for recording information signalsthereon, said disc-shaped recording medium being rotationally housed ina main cartridge body unit made up of an upper half cartridge and alower half cartridge abutted and connected to each other, said disccartridge comprising: a recording and/or reproducing opening provided insaid main cartridge body unit for exposing a signal recording region ofsaid disc-shaped recording medium at least across the inner and outerrims of the disc-shaped recording medium; a driving opening provided insaid main cartridge body unit for permitting intrusion of rotatingdriving means adapted for rotationally driving said driving rotatingmeans; and a shutter mechanism for opening/closing the recording and/orreproducing opening and the driving opening; said shutter mechanismincluding a first shutter member for opening/closing mainly saidrecording and/or reproducing opening and a second shutter member foropening/closing mainly said driving opening, said first shutter memberincluding a shutter portion for opening/closing said recording and/orreproducing opening and the driving opening, a movement causing portionfor causing movement of said shutter portion and an interconnectingportion interconnecting said shutter portion and the movement causingportion; said movement causing portion being moved along a lateralsurface of said disc cartridge for causing movement of the shutterportion.
 13. The disc cartridge according to claim 12 wherein saidlateral surface of said main cartridge body unit along which is movedthe movement causing portion is a surface of said disc cartridgeparallel to the loading/unloading direction with respect to saidrecording and/or reproducing apparatus.
 14. The disc cartridge accordingto claim 12 wherein said movement causing portion is resilient.
 15. Thedisc cartridge according to claim 12 wherein the shutter portion and theconnecting portion of the first shutter member are formed as-one witheach other.
 16. The disc cartridge according to claim 12 wherein theconnecting portion and the movement causing portion of the first shuttermember 25 are formed as-one with each other.
 17. The disc cartridgeaccording to claim 12 further comprising: a lock mechanism forinhibiting movement of said shutter mechanism lying at the position ofclosing said recording and/or reproducing opening and the drivingopening.
 18. The disc cartridge according to claim 17 wherein said meansfor releasing the lock of said shutter mechanism by said lock means isprovided on a lateral surface of said main cartridge body unit alongwhich is moved said movement causing portion.
 19. The disc cartridgeaccording to claim 18 wherein the means for releasing the inhibition ofmovement of said shutter portion by said lock mechanism is a firstprotrusion that appears and disappears on a lateral surface of said maincartridge body unit, said movement causing portion is a secondprotrusion moved along a lateral surface of said main cartridge bodyunit and wherein said first and second protrusions are positioned in arecessed groove formed along a lateral surface of said main cartridgebody unit.
 20. The disc cartridge according to claim 19 wherein saidfirst and second protrusions are arranged in this order when lookingfrom the disc cartridge inserting side into the recording and/orreproducing apparatus.
 21. A disc cartridge for housing a disc-shapedrecording medium adapted for recording information signals thereon,comprising: a driving rotating means; a main cartridge body unitincluding a recessed medium housing section for housing said disc-shapedrecording medium therein, a first wall section constituting the bottomof the medium housing section, a second wall section arranged facingsaid first wall section, a second opening formed in said second wallsection for facing a first opening formed in said first wall section, acut-out formed in the peripheral surface of the medium housing section,and a groove formed in continuation to said cut-out; and a shuttermember arranged between said first and second wall sections, saidshutter member including a shutter portion adapted for opening/closingan opening defined by said first and second openings, and a cut-outopening/closing portion formed in continuation to said shutter portionand arranged for extending from said cut-out to said groove foropening/closing said cut-out.
 22. The disc cartridge according to claim21 wherein said cut-out opening/closing portion is stepped in shape.